Vehicles go out of production for lots of reasons but most often it has to do with the bottom dollar for the manufacturers.

Chevy Caprice was stupid popular with law enforcement agencies. Seems most preferred them to the Ford Crown Victoria. The Caprice was discontinued for one simple reason- there was more profit in SUVs and they converted the plant that made the Caprice to start making more Tahoes and Suburbans.

And as far as a previous comment about all cars pretty much looking the same, it?s all about aerodynamics. Ultimately there is only one design that is as aerodynamic as you can make a car so if every manufacturer is striving to make the most aerodynamic vehicle then they are all basically pushing their design towards the same shape. Since there are strict fuel economy and emissions standards to be met the more aerodynamic a vehicle is the better it will do in those departments.